Theorem 2.17: ([1]})
Let \(M\)  be a hyperkähler manifold,
and \(S\subset H^{1,1}(M)\)  the set of all MBM classes of type \((1,1)\) .
Consider the corresponding set of hyperplanes
\(S^\bot :=\lbrace W=z^\bot \ \ |\ \ z\in S\rbrace \)  in \(H^{1,1}(M)\) .
Then the Kähler cone of \(M\)  is
a connected component of \(\operatorname{Pos}(M)\backslash \cup S^\bot \) ,
where \(\operatorname{Pos}(M)\)  is the positive cone of \(M\) .
Moreover, for any connected component \(K\)  of
\(\operatorname{Pos}(M)\backslash \cup S^\bot \) ,
there exists \(\gamma \in O(H^2(M,{Z}))\)  in the monodromy group of \(M\)  and
a birational model \(M^{\prime }\)  such that \(\gamma (K)\)  is the Kähler cone
of \(M^{\prime }\) .

